My as well as others opinions. First it was the Republicans that freed the slaves and there was a Civil war over that. At that time after the Civil War the ‘Yellow Dog’ Democrats were born. These Democrats were mostly from the Confederation and the Southern States, as they would not vote for a Republican for any reason at all and would rather vote for a ‘Yellow Dog.’
That ‘Yellow Dog’ voting for only a Democrat by the ‘white’ folks lasted in the Southern States till LBJ signed the Civil Rights legislation. The South was always counted for voting for Democrats, well at least the white folk. After LBJ signed the Civil Rights legislation two things happened and both involved Democrat voting to move to the Republican side.
First there was a fairly bright set of Democrats that felt that the time was right to make the world a safer place to live in than spending the USA money on Civil Rights. These folk were mainly Jewish and became known as the Neo Conservatives or as we now call them the Neo-Cons. The second thing that happened was the feeling of abandonment by the democratic folk for giving the ‘blacks’ more civil rights, doing away with the colored folk set of things which set the Blacks away from the Whites that the southern states did before then.
Therefore the Neo-Cons because they felt that the money spent by the USA should be to make the world a safer place to live as opposed to spending it on Civil Rights, and the southern white folks switching to the Republican party because giving ‘Blacks’ equal rights wasn’t what those folks wanted at all gave the Republican Party many ‘new’ voters.
However, many that were in the ‘old’ Republican party in the northern and other states like California where I am from went on to register as Independent as they now have no other place or party that ‘fits’ at all. I don’t agree with the Democrats or the Republicans at all now. One can call me an Ike, Nixon, Goldwater Republican, but not a Reagan Republican at all, and let alone any of the fragmented set that these days call themselves Republicans.